Cette thèse est dédiée à la cryptanalyse de l'AES (Advanced Encryption Standard) qui est l'un des systèmes de chiffrement par bloc les plus répandu dans le monde. Nous y présentons une nouvelle technique pour résoudre un type particulier d'équations spécialement conçu pour attaquer l'AES. Cette technique est basée sur l'algèbre linéaire ainsi que sur la technique de la " Rencontre par le Milieu " et offre pour un système donné, plusieurs algorithmes de résolution de complexités différentes mais prédictibles. Ainsi nous avons conçu un programme pour trouver l'algorithme le plus rapide. Dans un premier temps nous l'avons appliqué directement aux systèmes d'équations décrivant un nombre réduit de tours d'AES et avons trouvé de nouvelles attaques lorsque la quantité de couples clair/chiffré est très limitée, améliorant celles trouvées manuellement par d'autres chercheurs. La technique étant générale nous avons pu utiliser le programme pour étudier d'autres modèles comme celui des attaques par fautes et celui des attaques à clé choisie ainsi que d'autres primitives cryptographiques comme la fonction d'authentification Pelican-MAC et le système de chiffrement par flot LEX. Enfin nous présentons une généralisation des attaques de Demirci et Selçuk publiées à la conférence FSE2008 ainsi qu'un algorithme qui nous a permis de trouver les meilleures attaques de cette classe, avec certaines parmi les meilleures connues à ce jour. Cet algorithme repose sur l'utilisation du précédent programme afin de déterminer le nombre de valeurs prises par des sous-ensembles d'octets de clé ou des états internes ainsi que la complexité de les énumérer.

Les blocs cryptographiques utilisés dans les circuits intégrés implémentent des algorithmes prouvés robustes contre la cryptanalyse. Toutefois des manipulations malveillantes contre le circuit lui-même peuvent permettre de retrouver les données secrètes. Entre autres, les attaques dites " en fautes " se sont révélés particulièrement efficaces. Leur principe consiste à injecter une faute dans le circuit (à l'aide d'un faisceau laser par exemple), ce qui produira un résultat erroné et à le comparer à un résultat correct. Il est donc essentiel de pouvoir détecter ces erreurs lors du fonctionnement du circuit. Les travaux de thèse présentées dans ce mémoire ont pour objet la détection concurrente d'erreurs dans les circuits cryptographique, en prenant comme support l'implantation du standard d'encryption symétrique l'Advanced Encryption standard " AES ". Nous analysons donc plusieurs schémas de détection d'erreur basés sur de la redondance d'information (code détecteur), certains issus de la littérature, d'autres originaux utilisant un double code de parité entrée-sortie permettant l'amélioration du taux de détection d'erreur dans ces circuits. Nous présentons aussi une étude montrant que le choix du type du code détecteur le plus approprié dépend, d'une part du type d'erreur exploitable pouvant être produite par un attaquant, et d'autre part du type d'implémentation du circuit à protéger. Les circuits cryptographiques sont également la cible d'autres attaques, et en particulier les attaques par analyse de consommation. Les contre mesures proposés jusqu'à lors pour un type d'attaques, se révèlent la plupart du temps néfastes sur la résistance du circuit face à d'autres types d'attaque. Nous proposons dans cette thèse une contre mesure conjointe qui protège le circuit à la fois contre les attaques en fautes et les attaques par analyse de consommation.

It is widely recognised that security is a concern in the design of a wide range of embedded systems. However, security for embedded systems remains an unsolved problem, which could create greater challenges in the future than security for mainstream computers today. The promise of universal connectivity for embedded systems creates increased possibilities for malicious users to gain unauthorised access to sensitive information. All modern security protocols use private-key and public-key algorithms. This thesis investigates three important cryptography algorithms (RC4, AES, and RSA) and their relevance to networked embedded systems. Limitations in processing power, battery life, communication bandwidth, memory and costs constrain the applicability of existing cryptography standards for small embedded devices. A mismatch between wide arithmetic for security (32 bit word operations) and embedded data bus widths (often only 8 or 16 bits) combined with a lack of certain operations (e. g., multi precision arithmetic) highlight a gap in the domain of networked embedded systems security. The aim of this thesis is to find feasible security solutions for networked embedded system applications. The above mentioned cryptography algorithms have been ported to three hardware platforms (Rabbit RCM3000, Xilinx Virtex 4 FPGA with MicroBlaze softcore, and a Linux desktop machine) in order to simulate several real world scenarios. Three applications – bidirectional transmission with encryption and decryption for various payload length, unidirectional transmission with very short payload, and encrypted data streaming – were developed to meet the simulation requirements. Several timing results were collected and used for calculating the achieved throughput. The Rabbit hardware platform, which represents the lower end in this thesis, was able to perform the RC4 crypto algorithm with a throughput of about 155 kbit/s. Thus the RC4 crypto algorithm was proven to outperform the AES crypto algorithm by a factor of 5, with AES achieving a throughput of about 32 kbit/s with the same hardware platform. The throughput was similar with the streaming application and UDP data transport. Without performing a cryto algorithm, the streaming application was able to process up to 1.5 Mbit/s. RSA was not implemented on the Rabbit hardware platform. The MicroBlaze hardware platform outperformed the Rabbit system by a factor of 5 – 10. It reached a throughput up to 1.5 Mbit/s with RC4 and up to 130 kbit/s with AES. The RSA algorithm reached up to 0.8 kbit/s on this hardware platform, showing that public-key ciphers are only suitable for short payload data, such as the exchange of a session key. The Linux machine was included in this test only to provide a reference to a non embedded system. The Linux performance was better than the MicroBlaze system by a factor of between 67 – 770, and better than the Rabbit platform by a factor of between 645 – 3125. Both the RC4 and the AES crypto algorithm reached a throughput of up to 100 Mbit/s on the Linux machine, with a throughput of up to 130 kbit/s reached with RSA. Hence, the Rabbit platform combined with the RC4 algorithm is suitable, for example, for MP3 streams with up to 150 kbit/s. The Rabbit platform with the AES algorithm could be used for low quality audio streams, for example for speech announcements. If a higher throughput is required, for example for video streams, the MicroBlaze could be an appropriate platform with throughput of up to 1.5 Mbit/s. Low cost embedded systems like Atmel AVR are not suitable for processing cipher algorithms developed in C. It is widely recommended that assembly language is used to develop such platforms.

Ένας από τους πιο ευρέως γνωστούς αλγορίθμους κρυπτογράφησης είναι ο AES (Advanced Encryption Standard). Το πρότυπο κρυπτογράφησης AES περιγράφει μια διαδικασία κρυπτογράφησης ηλεκτρονικής πληροφορίας βασισμένη στην λογική της κωδικοποίησης ομάδων δεδομένων με κάποιο μυστικό κλειδί. Μέχρι τον Μάιο του 2009, οι μόνες επιτυχημένες δημοσιευμένες επιθέσεις ενάντια στο πρότυπο AES ήταν επιθέσεις πλάγιου-καναλιού σε συγκεκριμένες εφαρμογές. Η βασική ιδέα των επιθέσεων πλαγίου καναλιού είναι ότι κάποιος μπορεί να παρατηρήσει έναν αλγόριθμο ο οποίος εκτελείται σε ένα σύστημα επεξεργασίας και να εξάγει μερικές ή πλήρεις πληροφορίες για την κατάσταση του αλγορίθμου ή το κλειδί. Ένας συγκεκριμένος τύπος επιθέσεων πλάγιου καναλιού, cache επιθέσεις, βασίζεται στην παρακολούθηση της συμπεριφοράς της μνήμης cache των συστημάτων (την μετακίνηση των δεδομένων μέσα και έξω από την μνήμη cache). Σε αυτή την διπλωματική αναπτύχθηκε ένα πρόγραμμα κρυπτογράφησης/αποκρυπτογράφησης AES και μελετήθηκε η συμπεριφορά διάφορων μνημών cache μέσω ενός προσομοιωτή επεξεργαστή (Simplescalar) κατά την διάρκεια εκτέλεσής του. Σκοπός της διπλωματικής εργασίας ήταν να δείξουμε ότι το κρυπτοσύστημα AES είναι ευάλωτο σε επιθέσεις πλαγίου καναλιού κρυφής μνήμης. / AES (Advanced Encryption Standard) is one of the most popular cryptographic algorithms. AES describes a process of electronic data encryption based on encrypting data using a secret key. Up to May 2009, the only successful published attacks against AES were side-channel attacks. The main concept of side-channel attacks is that someone can observe an algorithm that is being implemented in a system and gain information about the state of the algorithm or the secret key. One particular type of side-channel attacks, cache-based attacks, is based on observing the behavior of the system’s cache memory (tha data that moves in and out of the cache memory). In this thesis an algorithm AES (encryption/decryption) was developed and we examined the behavior of different cache memories using a simulator (Simplescalar) while this algorithm was processing trying to figure out if AES is vulnerable to cache-based side channel attacks. This thesis shows if AES is vulnerable against cache-based side channel attacks.

The battery driven nature of wireless sensor networks, combined with the need of extended lifetime mandates that energy efficiency is a metric with high priority. In the current thesis we explore and compare the energy dissipation of di fferent processor architectures and how it is associated with performance and area requirements. The processor architectures are di erentiated based on the datapath length (16-bit, 32-bit, 64-bit and 128-bit) and the corresponding size of the data memories. Our study focuses on AES algorithm, and the indicated processor architectures support AES forward encryption, CCM (32/64/128), CBC (32/64/128) and CTR common modes of operation. In each processor architecture the instruction set is extended to increase the efficiency of the system. / -

Η εισαγωγή των νέων Τεχνολογιών της Πληροφορίας και των Επικοινωνιών (ΤΠΕ) στην εκπαίδευση άλλαξε σημαντικά τη μορφή και τη λειτουργία της. Με την υιοθέτηση των νέων τεχνολογιών αναπτύχθηκε και αναπτύσσεται ακόμα η ηλεκτρονική μάθηση (e-learning), m-learning και η εξ αποστάσεως εκπαίδευση απέκτησε μια νέα διάσταση και νέες δυνατότητες. Είναι χαρακτηριστικό ότι η ανοικτή και εξ αποστάσεως εκπαίδευση αποτελεί έναν από τους βασικούς προπομπούς της νέας εποχής στο χώρο της εκπαίδευσης. Η κινητή ηλεκτρονική μάθηση θα χαρακτηρίσει τις νέες στρατηγικές, τις πρακτικές, τα εργαλεία, τις εφαρμογές, και τους πόρους για να εκπληρώσει την υπόσχεση της πανταχού παρούσας, προσωπικής, και συνδεδεμένης εκμάθησης, καθώς βασίζεται στην ιδέα της εκμάθησης με κινητές συσκευές οπουδήποτε οποιαδήποτε στιγμή, παρέχοντας μεγαλύτερη ευκολία στην κίνηση, τη σύνδεση σε κάποιο δίκτυο και τέλος χαρακτηρίζεται άπό νέες στρατηγικές και τα εργαλεία. Επομένως, προσφέρει ανεξαρτησία. Στόχος της διπλωματικής εργασίας είναι να υλοποιηθεί ένα σύστημα που θα βασίζεται στα διεθνή τεχνολογικά πρότυπα για ανοικτή, σύγχρονη και ασύγχρονη εκμάθηση για κινητά τηλέφωνα και ειδικότερα για iPhones. Θα χρησιμοποιηθεί και επεκταθεί η πλατφόρμα ανοικτού κώδικα Moodle και το σύστημα θα πληρεί όλες τις τεχνικές προδιαγραφές καθώς τα κινητά τηλέφωνα απαιτούν ειδικές τεχνικές και λειτουργικές απαιτήσεις. Πιο συγκεκριμένα, αποσαφηνίζονται βασικοί όροι για την μάθηση και την εκπαίδευση, καθώς επίσης παρουσιάστηκαν ακροθιγώς και οι τύποι εκπαίδευσης και μάθησης. Στη συνέχεια, παρουσιάζεται η υφιστάμενοι κατάσταση στα παραδοσιακά Συστήματα Διαχείρισης Μάθησης και στα Προσαρμοστικά Συστήματα Ηλεκτρονικής Μάθησης. Αποφασίστηκε να χρησιμοποιηθεί ως βασικός πυρήνας του συστήματος ένα παραδοσιακό σύστημα διαχείρισης μάθησης, το Moodle, βασιζόμενοι σε μια αξιολόγηση (Sabine 2005) που διεξήχθει σε εννιά Εφαρμογές Ανοικτού Κώδικα (Open Source) εξ αποστάσεως εκπαίδευσης. Ο κύριος στόχος της αξιολόγησης ήταν οι ικανότητες και τα χαρακτηριστικά των συστημάτων αυτών στην προσαρμογή και την εξατομίκευση και το Moodle έλαβε τη μέγιστη αξιολόγηση σε πέντε από τα οκτώ κριτήρια που τέθηκαν. Στόχος αυτής της έρευνας ήταν να βρεθεί το καλύτερο σύστημα ηλεκτρονικής μάθησης ανοικτού κώδικα το οποίο θα μας επέτρεπε να αναπτυχθεί μια πλατφόρμα κινητής μάθησης που θα συνδίαζε τα πλεονεκτήματα των σύγχρονων Προσαρμοστικών Συστημάτων Ηλεκτρονικής Μάθησης, όπως η προσαρμοστικότητα και την εξατομίκευση με τα βασικά χαρακτηριστικά των παραδοσιακών Συστημάτων Διαχείρισης Μάθησης, όπως είναι η επαναχρησιμοποίηση και η ολοκλήρωση. Πραγματοποιήθηκε εγκατάσταση του Moodle σε διαθέσιμο server της σχολής Μηχανικών Η/Υ και Πληροφορικής και πραγματοποιήθηκε κατάλληλη επέκταση του με τέτοιο τρόπο ώστε τα μαθήματα να προσαρμόζονται στις δυνατότητες κάθε μαθητή, στους μαθησιακούς στόχους του, καθώς και στα επίπεδα γνώσης, και το τρόπο μάθησης του κάθε μαθητή, ενώ ταυτόχρονα να είναι προσβάσιμα και από κινητές συσκευές όπως iPhones και iPads. Για να επιτευχθεί η πρόσβαση στα μαθήματα της πλατφόρμας από κινητές συσκευές εγκαταστάθηκαν σε ένα iPhone οι εφαρμογές mPage και mTouch. Ύστερα από πειράματα που διενεργήθηκαν η εφαρμογή mPage παρουσιάζει πλεονεκτήματα έναντι της εφαρμογής mTouch και του web browser. Τα πλεονεκτήματα που εμφανίζονται και αναλύονται στην παρούσα διπλωματική οφείλονται στο γεγονός ότι η mPage επικοινωνεί με τη δική της web service και είναι σε θέση να ζητά μόνο τα δεδομένα που χρειάζεται. / The integration of the Information and Communication Technologies (ICT) has changed significantly the field of education. Due to the adoption of the new technologies, e-learning has been emerged and developed. As a result, distance learning has transformed and new possibilities have appeared while m-learning gives new potentials. The m-learning will feature new strategies, practices, tools, applications, and resources to fulfill the promise of ubiquitous, personal, and connected learning, as it is based on the idea of learning with mobile devices anywhere at any time, providing greater ease of movement, connecting to a network and finally filled by new strategies and tools. Therefore, it offers independence. The aim of the thesis is to implement a system based on international technology standards for open, synchronous and asynchronous learning for mobile phones and especially for iPhones. The open source platform Moodle will be used and be extended and the system will meet all technical specifications as well as mobile phones require specific technical and functional requirements. More specifically, initiallly this thesis clarify key terms of learning and education as well as present briefly the types of education and learning. Then, it presents the current situation in the traditional Learning Management Systems and Adaptive e-Learning Systems. Based on an evaluation (Sabine 2005) conducted in nine open source platforms of elearning management system, we decided to use as a core system of our platform, a traditional learning management system, the Moodle, The main objective of the evaluation was the skills and the characteristics of such systems to be adaptive and personalized. Moodle received the highest evaluation in five out of eight criteria. The objective of this research was to find the best system of e-learning open source which will allow us to develop a mobile learning platform that combines the advantages of modern e-Learning Adaptive Systems, such as adaptability and customization with the essential features of traditional systems Learning Management, such as reuse and integration. An installation of Moodle took place in a server of Computer Engineering and Informatics and an extension carried out so that the courses appear to be customized to each student, the learning objectives, and the levels of knowledge and learning styles of each student, while are accessible from mobile devices like iPhones and iPads. mPage and mTouch applications installed on an iPhone to gain access to the courses of the platform from mobile devices Following experiments carried out proved that mPage has advantages over the mTouch and web browser to the fact that mPage communicates with its own web service and be able to request only the data needed.

The purpose of this thesis work was to conduct a general research on existing security techniques and come up with a considerable algorithm for data security in cloud storage. Cloud storage is an infrastructure or is a model of computer data storage in which the digital data is stored in logical pools. It unifies object storage for both developers and enterprises, from live applications data to cloud archival. It help to save valuable space on PC computers or mobile devices and provides the easy storage and access of data anywhere in the world. However, just as the benefits of cloud computing abounds, so also are the risks involved. If data are not well secured or encrypted before deployment for storage in the cloud, in case of negligence on the side of the developers, then hackers can gain unauthorized access to the data. The behavior of existing security algorithms on data were studied, the encryption and decryption process of the each algorithm on data was studied and also their weaknesses against attacks. Apart from data encryption, security policies also plays an important roll in cloud storage which was also covered in this report. The research work was conducted through the use of online publications, literature review, books, academic publications and reputable research materials. The study showed that regardless of the challenges in cloud storage, there is still a suitable algorithm for protecting data against attack in the cloud.

Made available in DSpace on 2015-05-14T12:36:39Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1849104 bytes, checksum: 222c0377ddf502eb4a6c7fd2f658bdb1 (MD5) Previous issue date: 2013-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work addresses data encryption using Rijndael symmetric key encryption algorithm , which is used in Advanced Encryption Standard - AES. AES has massively widespread in computing, communications, and broadcast media applications, due to its robustness. By intensively using of all flavors and sizes of devices and networks, the AES has become the standard at the time of implementation and deployment of these applications when the major requirement, in addition to performance, is security, i.e. virtually all of those applications nowadays. In systems equipped with modern processors, even those on small devices, it is common to find some that perform the encryption and decryption procedures in software. With the "explosive" spread of addition of security layers in almost everything that is processed inside and outside of the devices, even on systems equipped with powerful computing resources, the possibility of performing these layers on (small) additional hardware resources, developed with specific purpose, has become attractive. This dissertation presents a study of the theoretical foundations involving AES, some architectures and implementations based on it and documented in the recent technical and scientific literature, as well as the methodologies and requirements for the development of its hardware implementation, in particular, focusing on mobile systems, where performance has to be achieved in low power consumption and small area scenarios. Reference models have been developed and functionally validated in high-level languages for each hierarchical architectural level compiled from the mentioned study. As a proof of concept, this work consisted in undertaking a project of an intellectual property of digital integrated circuit core (IP core) for the encryption/decryption procedures of AES, starting from the pseudocode level of the algorithms and going to the level of a digital integrated circuit core. Among the solutions studied from recent literature, modules and operations that could be replicated and/or reused were identified. A microarchitecture for the full AES was implemented hierarchically to the core level with standard cells placed and routed. The work also offers three implementation options for the block identified as the most complex: the S-Box. Results of performance and area were then presented and compared with those of literature. / Este trabalho aborda a criptografia de dados com chave simétrica com uso do algoritmo de criptografia Rijndael, que é utilizado no Advanced Encryption Standard - AES. Devido a sua robustez, tem se tornado massivamente difundido em aplicações computacionais, comunicação e de difusão de media. Abrangendo todos os tamanhos e sabores de dispositivos de rede, o AES tem sido o padrão na hora da implementação e disponibilização dessas aplicações quando o requisito principal, além do desempenho, é a segurança, ou seja, praticamente todas as aplicações digitais nos dias de hoje. Em sistemas de processamento dotados dos modernos processadores, mesmo os de pequeno porte, é comum encontrar sistemas que executam os procedimentos de criptografia e decriptografia em software. Com a proliferação "explosiva" da adição de camadas de segurança em quase tudo que é processado dentro e fora dos dispositivos, mesmo em sistemas dotados de poderosos recursos computacionais, tem se tornado atrativa a possibilidade de executar essas camadas em (pequenos) recursos adicionais de hardware, desenvolvidos com finalidade específica. Nesta dissertação, foram estudados os fundamentos teóricos, envolvendo o AES, arquiteturas e implementações documentadas na literatura técnica e científica recente, bem como as metodologias e requisitos específicos para fins de desenvolvimento de sua implementação em hardware, focando, em especial, os sistemas móveis, onde desempenho tem que ser conseguido com baixo consumo de energia e pouca área. Foram desenvolvidos e validados funcionalmente modelos de referência em linguagem de alto nível para cada nível de hierarquia arquitetural compilado do referido estudo. Como prova de conceito, este trabalho consistiu em realizar o projeto de uma propriedade intelectual de núcleo de circuito integrado IP-core, digital para realização dos procedimentos de criptografia/decriptografia do AES, partindo do nível do pseudocódigo dos algoritmos até o nível de um núcleo (core) de circuito integrado digital. Das soluções estudadas na literatura recente, foram identificados módulos e operações passíveis de serem replicadas/reusadas. Uma microarquitetura para o AES completo foi implementada hierarquicamente até o nível de núcleo com standard cells posicionado e roteado, contemplando ainda 3 opções de implementação para o bloco reconhecidamente o mais complexo: o S-Box. Resultados de desempenho e área foram apresentados e comparados.

During paper manufacturing, coating and adhesives are added to paper and cardboard to improve quality and durability. When the paper is later recycled or becoming new paper, the coatings may pollute the water used in the recycling process. Thus, it is important to know in which fraction these coatings finish during the process. In this study, laboratory made samples that mimic the repulping and paper making process is used. The different fractions of the processes were analyzed for a clay as well as a polymer coating. Metal content from clay coating is analyzed using inductively coupled plasma-mass spectrometry and microwave plasma-atomic emission spectrometry. For analyzing polymer coating, gas chromatography-mass spectrometry was used. From the result of the analysis the Reject sample, which was collected with a bigger mesh sieve in a repulping system, contained the highest amount of both clay and polymer coating. The other sample fractions from the repulping process and paper making process, did not contain as high mass content of either clay nor polymer coating.

The thesis is focused on implementation of aplication for secure telephone communication on data network. Application is developed for operating system Android. For call management is responsible signaling protocol SIP and for transfer of voice data is used protocol RTP. For security of call is first created cryptografic key for symetric cryptography. After generating key is established call, which is encrypted by symetric cipher AES. Encrypting between communicating sides is provided in application or on microSD card. Part of solution is measurement of speed of cryptographic primitives, which are used for secure call.